Radius dresser



Jan. 12, 1954 H H, GOTBEG 2,665,680

RADIUS DRESSER Filed Dec. so, 195o s sheets-sheet 1 l INVENToR. t F" #dl/Cy /1 'azzfer?. l y L'. J, B

` yFiled Dec. 5o,- 195o Jan. 12, 1954 H H. GorBl-:RG 2,665,680

RADIUS DRESSER 3 Sheets-Sheet 2 IN VEN TOR. Har/[1] 'akze/:g

f7 BY #Train/5K6 Jan. 12, 1954 H, G01-BERG i 2,665,680

' RADIUS DREssER 3 Sheets-#Sheet 5 Filed Dec. 30, 1950 Patented Jan. 12, 1954 Colonial Broach Company,

Detroit, Mich., assignor to.

Warren Township,

Y Mich., a corporation of Delaware Y 'Application December 30, 1950,'SeraINlo. 203,667

' 9 claims. (ci. 12s-1r) This invention -relates generally to av device for dressing grinding Wheels. and more particularly to a device for dressing the peripheral radius and adjacent tangential fiat surface. of a grinding Wheel.

- Many metalworking tools such as broaches and the like,y require frequentv sharpening `and resurfacing, and for this purpose an abrasive. grinding wheel is generally used. In many Vinstances grinding Wheels of the v type having a peripheral radius and adjacent tangential. flat surface are employed. In theresharpening of broaches it is extremely important that the grinding Wheel shape be accurately maintained at all times and that a smoothly dressed wheel be provided so that a keener'and smoother broach tooth cutting edge will be provided which in turn will produce a better nish on the broach part. Therefore, grinding Wheels must be frequently dressed and a diamond point dresser appears to perform. this result in thebest manner possible. Many grinding Wheel dressing tools and devices have been devised, but these have generally been too eX- pensive to manufacture, too complicated in construction and operation, too difficult. for an operator to use for quickly dressing the grinding Wheel, and often reduire complicated andtime consuming adjustments as the wheel wears.

It is, therefore, an object of this invention to provide a grinding wheel dressing device which may be mounted adjacent to or on the spindle housing of a grinding Wheel, which is sharpening breaches orA other similar tools, and which may be moved into or out of engagement with the grinding wheel in a very simple manner, so as to engage the grinding wheel at the proper point for the dressing thereof.

It is a still further object of this invention to provide a dressing tool of. the aforementioned type, inwhich'a diamond tip toolis employed for dressing the grinding Wheel. and in which the peripheral radius of the grinding wheel may be dressed :by the actuation of one lever, `and-the fiat surface may be dressed by the actuation of another lever, without the'necessity of any special adjustments or complicated aligning of the de'- vicevvith the grinding Wheel, and Without any concern of the dressing tool not properly vdressing the grinding Wheel.

It is a still further object. of thisinvention to provide a dressing tool. device of the aforementioned type which can dress. grinding wheels of diiferent sizes and shapes in a rapid, ecient and simple manner.

Itis a still further object Vof this inventionto provide; a dressing device of the aforementioned type.,y which is mountable on the grinding wheel spindle housing so-that irrespective of the adjusted position of the housing and wheel the .dresser will. be in position to dress thewheel without having its. setting disturbed.

YIt is. a. stillV further object of: this invention to providea device ofthe aforementioned type which is exceptionally sim-ple and inexpensive to manufacture, and is the most simple and efficient to use of vall dressing. devices of this type heretofore known.y

These and other objects of this invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which;

Figure lr is a top plan. view of the dressing device of this invention supported in a position to dress a grindingwheel. Y

Fig. 2 is .a side elevational view of the structurel illustrated in Figure Lshowing the dresser disposed'above a wheel to be dressed.

Fig. 3. is a reduced side elevational View showing; the dressing device mounted onA the spindle housing of a grinding wheel. y

Fig. 4 is an end elevational view of the structure illustrated in Fig. 3.

Fig. 5 is an enlarged sectional viewof the structure. illustrated in Figure 1, taken along the line 5-5 thereof; j

-Fig.. (i.v is an enlarged sectional view of the structure illustrated in Fig. 2, taken along the line 6 6 thereof;

' Fig. 7 is a sectional view of the structure illustrated in Fig.. 2 'taken along the line G-S there- Fig. 8 is afront elevational view of a portion of the device of this invention, showing the diamond tip in engagement with the peripheral radius of a grinding Wheel at the start of the dressing operation;`

Fig. 9 is a view similar to Fig. 8, showing the position of the parts after of the wheel has been partially dressed; vand Fig. l0 isa view similar to Figs. 8 and 9, showing the position of the parts after the radius has been' dressed and before the grinding wheel tangential flat surface rvhas been dressed. `Referrngnow to the drawings, it will be seen that the dressing device is illustrated at l and is supported onthe'upper end of a post 2,` the lower end of which is removably and adjustably connected at -3 with a holder and vdust shield 4; which vin turn is connected with the body or I lQusing ,5 ofspindle 6,1` which rotatably drives a the .peripheral radius grinding wheel 'l for sharpening breaches or the like. The dressing device l includes a horizontallv extending support member 8. which comprises an inner elongated. platelike portion 9 from which an outwardly extending square shaftlike portion le extends.

The shaft portion IIl extends slidably through an opening U of a. blocklike member I2. The blocklike member .I2 abuts one side of a second blorklike member I3. which is supported on the upper end of the post 2 in a manner which will hereinafter appear. The block members I2 and I3 are secured together by means of a nut and bolt Hi. and a nin I5 is suonorted in the block member I9. and one end thereof lextends above a shoulder or stop surface I5. below the to'o surface of block I3. rThe shoulder or surface I6 engages the nin I5 when the block members are in their normally disposed aligned. side by side position. By loosening the nut and bolt I4 the block member I2 may be swung about the axis of the bolt relative to the block member I3 so as to swing the dressing device upwardly away from the grinding wheel. for reasons which will hereinafter appear. The pin I5 therefore acts as a locator or stop to enable duick positive realignment of the block members I2 and i3 when the device is to be used to dress a grinding wheel.

The shaft portion IB of the member 8 has a gear rack I1 secured to the bottom face or side thereof, which meshes with a gear I 8 mounted on a shaft I9 which projects through the front side of the block member I2. and has an operating knob 2B connected. therewith. If the knob 2B is rotated. the member B will be adjusted horizontallv relative to the oost 2. A set screw 2l is provided in the upper portion of the block member I2. and adapted to engage the shaft portion lil to lock the dressing device in any adjusted position against accidental hori'zontal movement. The upper end ci the post 2 extends through a vertical opening 92 in the block member I3 and has a gear rack 23. secured to one vertical face thereof. which meshes with a gear 2d carried on a shaft 25 which has one end extending beyond the back face of the block member I3. An operating knob 2S is connected with the projecting portion of the shaft and may be rotated to adjust the block members I2 and. I3 vertically on the post. A set screw 21 is threaded into block member i3 for engaging the post 2 to positively lock the block. members and the dressing device in anv adjusted position relative to the post. Thus, with the aforementioned construction, the dressing device may be adjusted. horizontally and verticallv relative to the post, for reasons which will hereinafter appear.

A housing member 29 is adiustahly secured to one face of the plate portion 9 of the member 8, by any suitablemeans such as cap screws 3I, as will be hereinafter described. The outer face of the housing is suitably recessed at 33 to provide ways in which a movable slide element 35 is positioned. Gibs 31 are secured to the outer .face of the housing 29 by cap screws 38 to retain the movable slide member 35 within the ways and guide its vertical movement. A gear rack 39 is secured to one side face of the movable element 35 and meshes with a gear 4I, which is rotatably supported in the housing by a suitable pin or shaft 43. One end of the pin or shaft 43 extends outwardly through the housing 29 and a gib 31, and has a handle 45 connected thereto which, when actuated, will rotate the gear 4I to 4 cause the slide element 35 to move vertically in the housing Ways 33.

The direction or angle of movement of the slide element 35, may be varied or adjusted by rotatably adjusting the housing 29 on the supporting member 8. This is accomplished by loosening the cap screws 3|, one of which extends through an arcuate slot 41 in the plate portion 9 of the member 8, and the other of which is located adjacent the center of the slide element. After the cap screws SI are loosened the housing 29 can be rotated about the center cap screw 3l to the desired rotative position with respect to the supporting member 8, and in order to accurately determine this relationship the member 8 is provided with an index scale 49. A leaf spring 5I is provided for irictionally retaining the movable element 35 in its adjusted vertical position, and the spring is disposed in a recess 53 in the housing and engages vthe opposite side face of the movable element from that on which the gear rack 39 is mounted. If the handle 45 is actuated, the slide element 35 will be moved up and down relative ,to the housing 29, for reasons which will hereinafter appear.

A pair of spaced parallel links 55 and 51 are disposed adjacent the outer face of the slide element 35 and extend generally in the direction or the slide element 35, although they do not necessarily extend parallel to the direction of the movement of the slide element. The links are provided with inwardly extending projection portions 53, 6I and 53, which are spaced from each other equal distances 'lengthwise of the links, and the projection portions SI are disposed intermediate the ends of each link and the projection portions 59 and 63 are disposed adjacent the upper and lower ends of each link, respectively. Disposed between the outer face of the slide element 35 and the upper ends of the links 55 and 51, is an inverted triangularly shaped plate element 65. The opposite ends of the base of member 55 are pivotally connected to the opposed projection portions 59 of the links 55 andV 51, by means of suitable pivot pins or cap screws 61, and the lower or apex end of the member S5 is pivotally connected to the outer face of the slide element 35 by means of a pivot pin or cap screw 59. A similar inverted triangularly shaped plate member 1I is disposed below the triangular member 65, between the links 55 and 51 and. the slide element 35, and has the opposite ends of its base pivotally connected to the link projection portions 6I by means of suitable cap screws or pivot pins 13 and its apex end pivotally connected with the slide element by means of a suitable pivot pin or cap screw 15. A third member 11 extends between the lower ends of links 55 and 51 and is pivotally connected to the projection portions 63 of the links by means of suitable pivot pins or cap screws 19. While the member 11 may be of any suitable shape, it is illustrated, as can be best seen in Fig. 6, as having an outwardly projecting horizontal portion 8i, which has a threaded vertically extending aperture 63 therein, in which the upper end of a tool holder is threaded. The tool holder 35 may be vertically adjusted in the member 11 and can be secured in a desired position by means of a set screw 89. The tool holder 85 is centrally bored at 9i and a rod y93 is inserted into the lower end of the bore and carries a diamond tip 95 on the lower end thereof. Set screw 91 secures the rod in the tool holder 85. The tool holder 85 may be threaded inwardly or outwardly in member 11 for reasons tip is moved below the acontece which will hereinafter appear and :a `button ,98 is disposed in the upper.A endof aperture 83 and is used as a base point to measine or ldetermine the adjusted position ofthe diamond tip; I

vt5 and 1| on the movable slide 35, so `as to cause the parallel links 55 and 51 to swing 4'in a parallel relationship at all times,A so as to move the member 11 and the diamond tip 95' about a predetermined radius. the same distance belowthe cap screws '19 as the cap screws 69 and 15 are disposed below the cap screws 61 and 13 respectively,v the diamond tip will move about a point or center and will not scribe a radius. of any dimension. If ythe tool holder 85 is adjusted soas to move diamond tip 95 retical center, it will Vscribe a radius Aabout the center point in accordance with its adjusted distance above the center point. .If the 'diamond center point, it will scribe a reverse orv concave radius about the center point, in accordance with its adjusted position.'

Therefore, `the diamond tip 95 will move about a radius in accordance with its adjusted position to the theoretical center Vpoint of member 11, when the handle 99 is moved to actuate the members B5 and 1| and the links 55 and 51 pivotally connected therewith.

The device of this invention can be used to dress grinding wheels of various types and shapes but the grindingwheel 1 is illustrated in Figs.

lengthwise of they links- If thev diamond tip 95 is disposed Y andy so interconnected above vthe aforementionedpoint or' theoy l5 engages the shoulder or stop surface I6.

`ments made by actuating knobs Y sure that Athe diamondtip will properly engage iyand dress the wheel.

The links are so spaced that the diamond tip will the klinks have moved their engage each other. By then actuating the lever 45, so as to move the slide element downwardly, the diamond tip will move along the flat surface |05 to properly dress the same. The fiat surface on the opposite side of the wheel from surface |05 could, of course, also be dressed,r if the housing member 29 were rotated so that the slide member would move parallel thereto. quire a change of setting of the device.

It will thus be seen that once the dressing device has been.V mounted onthe spindle housi and adjusted as described above, the operator thereafter need not make any ad'- justments on the device, except the minute adjustments with knobs to bring the diamond tip into engagement with the peripheral edge of the grinding wheel and swing the lever 99v so as to cause the parallelogram linkage to move the diamond tip about the desired radius, and then thereafter actuate the lever so as to move the diamond tip along the grinding wheel :dat surface so as kto dress the same. The dressing device can be. moved out of interference with the grindingwheel and the wheel flat surface |05.

be so "positioned when maximum distance and sharpening of thebroach or lthe like may be 4con,- tinuedwithout interference froml the dressing device, `by loosening nut andbolt I4 and swinging block member I2 andthe device upwardly away from the grinding wheel. When it is desired to again dress the wheel the device and block member' l2 is swung downwardly until pin nutand bolt I4 is then tightened and adjust- 20 and 26 to in- The grinding wheel is `then dressed by operating levers or handles 45 S-10 as having a peripheral radius |03 and an adjacent flat `surface |05, which extends tangentally from one side of the radius |63. In order to dress the grinding wheel radius l|93 and surface |05, the housing 29 is the supporting member 8, sof that the slide element 35 will move in a direction parallel to the grinding wheel flat surface |05. Thedevice is then positioned, by rotating knobs 20 and 25 so that when thehandle 45' the diamond tip downwardly, the grinding wheel rad'us |03.

the tip will engage By then adjusting the diamond tip rod holder relative to member 11, so as to position the'tip 95 a predetermined distance yfrom the buttons and :thus from the point or center'V about which lit will rotate, in accordance-with the sizeof .the radius of the grinding wheel, the device isready 'to dress the grinding wheel and will not require further adjustments.` The lever 9.9 is then actuated so as to position the diamond tip in engagement with the radius |03, as shown in Fig. 8, and by moving the lever,99 counterclockwise, as viewed in Figs. 8 and 9, the diamond tip will move over the grinding Wheel peripheral edge or radius |03 to properly dress thesame, and when the lever is, as shown in Fig. 10, in its fully swung posi tion, so that the links are in engagement with each other and cannot move any further, the axis of the diamond tip rod 93 will be at right angles to the direction of movement of the slide element 35, and thereafter the diamond tipV will be disposed at right angles to the -grinding is' actuated to bring.

rotated relative to and99. After the wheel is dressed the .device can again be moved out of interfering relation with the wheel and the grinding operation on the broach can be continued. The dressing de- -vice of this invention therefore permits an operator to quickly and'easily dress the grinding wheel in a positive and efiicient manner and to av positive and definite form, without the necesappreciable time to carry out the dressing operation. Also as the device of this invention is mounted on the grinding wheel spindle body or housing, the setting of the dresser will not be disturbed if the grinding wheel and spindle body are swung at an angle, either horizontally or vertically, as is necessary in the sharpening of broaches or the like, whether the latter'` be cylindrical or fiat. Thus the s wheel dressingoperation can take place in any angular position of the grinding wheel spindle without remountingor removing the dresser.

What .is claimed is: Y

l. A device for dressing the radiused p eral edge and adjacent flat surface ci a i wheel; including supporting structure adapted to befmounted adjacent to the grinding wheel, elongate guides carried by said supporting structure, amovable element mounted in said guides on said supporting structure for rectilinear movement in a predetermined direction parallel the fiat surface of the grinding wheel, a pair of parallel spaced linksy adjacent said element on the side `away from said supporting structure, three transversely extending members spaced the length from each other in the direction of This would, of course, ref grinding wheel 20 and 26 and only need TheY .grinding wheel,

of said links, means pivotally connecting each of said members with each of said links, means pivotally connecting two of said members to said .movable element, means carried by sai-:l third member for carrying and supporting a tool for dressing said grinding wheel, and handle means connected with one of said two members for rotating said members and links on the movable element, whereby a parailelogram linkage arrangement is provided, which, when said handle is actuated, will move said third member and a dressing tool when the latter is connected therewith, so that said dressing tool will travel on a predetermined radius to dress said radiused peripheral edge of the grinding wheel, and whereby said element may thereafter be actuated to cause the tool to dress the iiat surface of said said third member being disposed adjacent cne end of said element so that said element will be out of interfering relationship with respect to a grinding wheel being dressed.

2. A device for dressing a grinding wheel radiused peripheral edge and an adjacent flat surface which extends tangentially from said radiused peripheral edge, including supporting structure adapted to be mounted adjacent to the grinding wheel, elongate guides carried by said supporting structure, a movable element mounted in said guides on said supporting structure for rectilinear movement in a predetermined direction parallel to the flat grinding wheel surface, a pair of parallel links adjacent said movable element on the side away from said supporting structure and spaced from each other transversely of the longitudinal axis ofthe movable element, a pair of members spaced from each other longitudinally of said links, pivot pin means pivotally connecting each of said members to each of said links, pivot pin means connecting each of said members to said movable element, said last pivot pin means being spaced longitudinally of said links from the pivot pin means connected to said links, a third member spaced from said two members longitudinally of said links, pivot pin means connecting said third member to each of said links, said pivot pin means connecting said first, second and third members to said links being equally spaced from each other and being in alignment with each other, a grinding wheel dressing tool carried by said third member and being adapted to have the working portion thereof disposed in alignment with the pivot pin means connecting said first and second members to said movable element, one end of said dressing tool being disposed beyond the adjacent end of said element so that said element will be out of interfering relationship with respect to a grinding wheel being dressed, handle means connected with one of said members for actuating the parallel linkage system for rotating said members about the pivot pin means connecting them to said movable element so that movement of said handle will cause said dressing tool to follow a predetermined arcuate path for dressing the radiused peripheral edge of the grinding wheel, after which said element may be actuated to cause said dressing tool to dress the adjacent at surface of said grinding wheel.

3. A device for dressing a peripheral radiused edge and adjacent at tangential surface of a grinding wheel, including supporting structure adapted to be mounted adjacent to the grinding wheel, elongate guides carried by said supporting structure, a movable element mounted in said guides on said supporting structure for rectilinear movement in a predetermined direction parallel to the at surface of the grinding wheel, a pair'of parallel links spaced generally transversely of said element and disposed adjacent thereto on a side away from said supporting structure, a triangularly shaped member disposed between said links and said movable element adjacent onel end of said links, pivot pin means pivotally connecting said links to said triangular member adjacent the opposite ends of the base of said Vtriangular member, pivot pin means connecting said movable element to said triangular member adjacent the apex thereof, a secondtriangular member disposed between said links and movable element intermediate the ends of said links, pivot pin means pivotally connecting said links to said second triangular member adjacent opposite ends of the base thereof, pivot pin means pivotally connecting said movable element to said triangular member adjacent the apex thereof, the pivot pin means connecting each of said triangular members to said links being spaced lengthwise of said links the same distance from the respective pivot pin means connecting each of said triangular members to said movable element, a member extending between said links adjacent the opposite end thereof, pivot pin means pivotally connecting said third member to said links, the pivot pin means pivotally connecting said links to said first, second and third members being equally spaced lengthwise of said links, said third member being adapted to carry a tool for dressing the grinding wheel, said third member being disposed adjament one end of said element so that said element will be out of interfering relationship with respect to a grinding wheel being dressed, handle means connected with one of said members and actuatable to cause said first and second members to rotate on said movable element and impart rotative motion .through said links to said third member to cause a dressing tool carried thereby to move through a predetermined arc, so as to dress the radius of the grinding wheel, while thereafter said movable element may be moved parallel to the tangential iiat surface of said grinding wheel to dress the same.

4. A device for dressing a peripheral radius and adjacent tangential iiat surface of a grinding wheel, including supporting structure adapted to be mounted adjacent to the grinding wheel, elongate guides carried by said supporting structure, a movable element mounted in said guides on said supporting structure for rectilinear movement in a predetermined direction parallel to the flat surface of the grinding wheel, a pair of parallel spaced links adjacent to the said movable element on a side away from said supporting structure, a member extending between and pivotally connected `to said links, a dressing tool carried by said member, one end of said dressing tool being disposed beyond one end of said element so that said element will be out of interfering relationship with respect to a grinding wheel being treated, two additional members extending between and pivotally connected to said movable element and to said links to maintain said link in a parallel relationship at all times and to cause said links to move in a predetermined path relative to said movable element so as to cause the working portion of said tool to follow a predetermined radius when said links are actuated.

9 5. A-device'for dressing fa" peripheral radius and adjacent tangential flat surface of a grinding wheel, including supportingvstructure adapted to be `mounted adjacent tothe grindingwheel, elongate guides .carried by said supporting structure, a movable element mounted in said lguides on said supporting structure for rectilinear movement in a predetermined direction parallel to the flat surface of the grinding wheel, ka pair of parallel spaced links vadjacent to Vsaid lelement on a side away Yfrom said supporting structure, three transversely extending @members spaced from each other 'in the direction loi? the length of said links, means pivotally connecting each of said members with each of said links, means pivotally connecting two of `said members to said movable element, a grinding wheel dressing tool carried by said third member, one end of said dressing tool being disposed beyond one end of said element so that said element will be out of interfering relationship with respect to a grinding wheel being dressed, and means connected with one of said members for actuating said links and connected members so as to cause said members to rotate on said movable element and thereby cause said third member and the dressing tool carried thereby to rotate about a predetermined radius, said links and members being so spaced that when said links are moved in one direction so as to engage each other, the tool carried by said third member will be disposed at right angles to the direction of movement of the movable element.

6. A device for dressing a peripheral radius and adjacent tangential flat surface of a grinding wheel, including supporting structure adapted to be mounted adjacent to the grinding wheel, a slide supporting member, means connecting said slide supporting member with said supporting structure for angular adjustment relative thereto, a slide element, means connecting said slide element with said slide supporting member to permit said slide element to move relative to said supporting member in a predetermined lineal direction parallel to the fiat surface of the grinding wheel, a gear rack con- Y nected with said slide element, a gear rotatably supported on said supporting member and adapted to be rotated so as to move said slide element relative to said supporting member, a pair of parallel spaced links adjacent said element, three transversely extending members spaced from each other in the direction of the length of said links, means pivotally'connecting each of said members with each of said links, means pivotally connecting two of said members to said slide element, a grinding wheel dressing tool carried by said third member, and means connected with one of said members for actuating said links and connected members so as to cause said members to rotate on said slide element and thereby cause said third member and the dressing tool carried thereby to rotate about ya predetermined radius.

7. A device for dressing the radiused peripheral edge and an adjacent ilat surface of a .grinding wheel, including post means for supporting the device in a desired location relative to the grinding wheel, a member movably mounted on said post means, cooperating means on said post means and said member actuatable to adjust the position ofr said member on said post means, an element supported in said member for movement in a direction transversely of the direction of movement of said member on ene-aseo vsaid member-,.zslide means mounted on said element for movement in a predetermined direction, a pai-r :of parallel .spaced links adjacent to said slide means, three transversely extending members spaced from each other in the direction 'ofA the length oi said links, means pivotally connecting each of said members with each of said links, `means Vpivotaily Aconnecting two oi"k said members tosaid `movable slide. means, said third member being adapted to 'carry and support a tool for dressing said grinding wheel, and handle means connected with one ofsaid two members for rotating said members and links on said slide means.

8. A device for dressing a peripheral radius and adjacent tangential iiat suri'ace orl a grinding Wheel, including supporting structure vadapted to be mounted adjacent to the grinding wneel and dening elongateguides, an element mounted in said guides for rectilinear movement 1nV a predetermined direction parallel to the nat surface of the grinding wheel, a pair of parallel spaced links adjacent to said element on a side away from said supporting structure, three transversely extending members spaced from each other in the direction oi the length of said links, means pivotally connecting each oi' said members with each of said links, means pivotally connecting two of said members to said movable element, a grinding wheel dressing tool carried by said third member, one end or' said dressing tool being disposed beyond one end of said element so that said element will be out of interfering relationship with respect to a grinding Wheel being dressed, and means connected with one of said members for actuating said links and connected members so as to cause said members to rotate on said movable element and thereby cause said third member and the ldressing tool carried thereby to rotate about a predetermined radius.

9. A device for dressing a peripheral radius and adjacent tangential ilat surface of a grinding Wheel, including supporting structure adapted to be mounted adjacent tothe grinding wheel, elongate guides carried by said supporting structure, a slide element mounted on said supporting structure for rectilinear movement in a predetermined direction parallel to the flat surface of the grinding wheel, means including a rack and gear for moving said element, means connected with said supporting structure and said element permitting said element to be angularly vadjusted about said gear relative to said supporting structure and locked in a predetermined angular position, a pair of parallel spaced links adjacent to said element on aside away from said supporting structure, three transversely extending members spaced from each other in the direction of the length of said links, means pivotally connecting each of said members wit each of said links, means pivotally connecting two of said members to said movable element, said third member carrying means adapted to support a grinding Wheel dressing tool, said third member being disposed adjacent one end of said element so that said element will be out oi interfering relationship with respect to a grinding Wheel being dressed and means operatively connected with said links for actuating said links and connecting members so as to cause said members to rotate on said movable element and thereby cause said third member and the dressing tool carried thereby to rotate about a predetermined radius.

HARRY H. GOTBERG.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date Lloyd Oct. 31, 1922 Gardner Dec. 1, 1925 Durkee Apr. 6, 1926 Williams Aug. 17, 1926 Number Number lo 12,923 2 1,653 272,704 535,657 

